Don't confuse energy with velocity. The 45-70, in particular, has a massive slug compared to the other cartridges you mentioned. Even slow, it has a lot of momentum and cuts a wide swath. The factory loadings of 45-70 tend to be anemic due to the age and design of a lot of the firearms which are still around chambered for it. In modern weapons, loaded to its potential, it will drop pretty much anything hit by it.